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71 Cards in this Set
- Front
- Back
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74. What is the name of the structure made from a sperm and an oocyte?
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Zygote
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75. What is the process that enables the sperm to fertilise a secondary oocyte?
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Capacitation
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76. How does the secondary oocyte get through the uterine tubes?
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Waving action of cilia
Fluid waves created by the cilia within the tube Peristaltic contractions of the smooth muscle |
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77. How fast do sperm move?
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4mm per minute
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78. How many sperm are generally ejaculated?
How many make it to an oocyte? |
Millions
200-300 |
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79. What is the 1st action that is taken when the sperm reach the secondary oocyte?
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They force their way through the corona radiate (outside layer)
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80. What are the receptors that the sperm bind to in the zona pellucida called?
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Zp3
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81. What is the reaction called where the head of the sperm release their contents in the zona pellucida?
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Acrosomal reaction
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82. What are the enzymes released in the acrosomal reaction and what do they do?
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Acrosin & Neuraminadase
Degradate the zona pellucida |
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83. How many sperm must release acrosomal enzymes to allow degradation of the zona pellucida?
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A large number
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84. What is the oocyte cell membrane called?
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Oolemma
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85. What is the process that ensures only one sperm fuses with oocyte?
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Syngamy – one sperm enters
Polyspermy – prevention of several sperm passing through 2 phases of polyspermy:- Fast block to polyspermy – influx of sodium and calcium ions into the oocyte and depolarises the oocyte Slow block to polyspermy – extra calcium released in oocyte forms a hardshell around the oocyte which is not penetrable to other sperm. Zp3 receptors deactivated |
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86. What part of the sperm is released into the oocyte and where from?
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The sperm fuses to the oocyte
The sperm’s nucleus, centriole, mitochondria, intracellular substances pass through The sperm’s nucleus and centriole are the only portions that are used in the development of the oocyte |
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87. What is the process of decondensation?
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Di-sulphide bonds are broken and genetic material passes to the cytoplasm of the oocyte
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88. What is the process of how the male and female chromosomes join together?
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23 male chromosomes are surrounded by a nucleus where they replicate to form 23 chromosomes each with 2 sister chromatids
Male centriole replicates and migrates Female chromosomes from ovum form a haploid female pronucleus DNA replication forms a female pronucleus with 23 chromosomes formed from 2 sister chromatids 2 pronuclei migrate to each other to go through 1st mitotic cleavage |
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89. What is cleavage of the zygote?
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Haploid nuclei merge –1x 46F, 1x 46M
Diploid – 1 x (46F + 46M) Mitosis Diploid – (2x23F, 2x23M) Mitosis – 2 x (23F, 23M) |
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90. When the zygote has divided to 12-16 cells it is called a ?
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Morula – surrounded by zona pellucida
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91. When the zygote bonds with the uterus it changes into a?
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Blastocyst
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92. The blastocyst contains what areas and what will these areas later become?
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Inner cell mass>>>>embryo
Blastocyst cavity(blastocoel) Trophoblast>>>foetal portion of placenta |
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93. What does the term embryo used for?
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Developing human up to 8 weeks
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94. What is the definition of twins?
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Two embryos that develop in uterus instead of one
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95. What is an embryo after 8 weeks called?
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Foetus
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96. What are the 2 types of twins?
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Identical (monozygotic) twins – original embryo cleave from original embryo and develop separately but with one embryo–b4 8 days
Fraternal (dizygotic) twins – two oocytes are fertilised and each have a placenta |
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97. What is the definition of hatching?
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The embryo bursts out of the zona pellucida
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98. How does hatching occur?
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Release of proteolytic enzymes from blastocyst and the degradation of zona pellucida
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99. What is the process of implantation?
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Blastocyst changes to a chorion >>>>releases chemicals to get through the endometrium>>>endometrium develops extra blood vessels and tissues>>>synctiotrophoblast forms sinuses and fills with maternal blood>>>cytotrophoblast secretes Beta human chorionic gonadotrophin>>>Maternal portion of placenta
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100. What does the blastocyst separate into?
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Cytotrophoblast – surrounds the blastocyst
Synctiotrophoblast – penetrates the endometrium and pull blastocyst into uterine lining |
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101. How does the synctiotrophoblast penetrate the uterine lining?
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The synctiotrophoblast secretes chemicals that degrade the endometrial cells and allows the blastocyst to penetrate the connective tissue layer of the endometrium.
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102. What are the synctiotrophoblast and cytotrophoblast collectively referred to as?
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Chorion
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103. What is Beta HCG used to test for?
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Pregnancy
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104. What is the function of Beta HCG?
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The function of Beta HCG is to prolong the secretion of Oestrogen & Progesterone from the corpus luteum of the ovary
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105. What is the term for the formation of the placenta?
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Placentation
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106. What is the placenta?
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It is the combination of embryonic portion (Chorionic villi) and the maternal portion (the endometrium & its blood supply)
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107. How is the placenta connected to the embryo?
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It is connected by the connecting stalk which turns into the umbilical cord
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108. What is the process of embryonic development?
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Inner mass of the embryo constantly divides>>>bilaminar disc (epiblast & Hyopblast)>>>Amniotic cavity develops between the layers>>>hypoblast forms a yolk sac>>>connecting stalk connected to cytotrophoblast>>>epiblast forms trilaminar disc(ectoderm, mesoderm, endoderm)
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109. What is the process of neurulation referring to?
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It is the formation of the neural tube from the ectoderm
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110. What is the embryo surrounded by for shock absorption, temperature regulation & adherence to the surrounding membranes?
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Surrounded by ambiotic membrane filled with ambiotic fluid.
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111. What is the role of the yolk sac early on?
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Formation of blood and sex cells
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112. What is in the connecting stalk?
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Arteries and veins
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113. What are pharyngeal arches and bulges?
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Pharyngeal arches – bulges on the surface of the embryo
Pharyngeal pouches – internal bulges of the pharynx>>>become the head & neck |
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114. What area of the embryo forms the primitive heart and blood vessels and what is this area called?
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Mesoderm forms the primitive heart and blood vessels
The area is called the cardiac eminence 3 weeks the heart beats |
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115. What is the name of the formation of bones of the embryo?
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Osteogenesis
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116. How are bones of the embryo formed?
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By either intramembranous or endochondrial ossification
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117. The embryonic development of the majority of the skeleton is?
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Endochondrial ossification
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118. What type of bones does intramembranous ossification form?
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Formation of flat bones that consist of two flat plates of compact bone tissue (internal & external plates) and inner section of spongy bone called the diploe
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119. How are sinuses formed in bones?
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The diploe is destroyed and replaced by sinuses (holes)
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120. How does endochondrial ossification occur?
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Hyaline cartilage in basic shape of bone>>>>>Centre of bone develops primary ossification centre (diaphysis)>>>develop epiphysis (secondary ossification centres)>>>cartilage at end of bones
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121. When does the brain, glands 7 digestive system start to develop?
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Week 4 onwards
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122. What happens in weeks 5-8 of embryonic development?
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Nervous tissue of brain
Heart from 2 chambers to 4 chambers Ears & eyes External genitals Internal organs Limbs and extremities Elimination of tail |
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123. Where does fertilisation most commonly occur?
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The uterine (fallopian) tube
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124. How long is secondary oocyte viable for after ovulation?
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1 day
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125. What happens in the capacitation process?
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The sperm are acted upon by secretions in the femal reproductive tube which result in the removal of cholesterol, glycoproteins and proteins from the head of the sperm.
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126. Condensation/decondensation occurs within the oocyte following fertilisation
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Decondensation
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127. The oocyte/sperm contribute the centriole which is necessary for cleavage
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Sperm
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128. The fertilised secondary oocyte completes meiosis I/II
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Meiosis II
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129. The oocyte is called an ovum before or after completing meiosis II
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After
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130. The pronuclei are haploid/diploid?
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Haploid
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131. DNA replication occurs in which of the male/female pronucleus?
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Both
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132. The daughter cells that are produced by cleavage are diploid or haploid?
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Diploid
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133. The zygote divides by mitosis/meiosis?
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Mitosis
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134. What is one way that the zygote travels along the uterine tract?
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Cilia waving
Fluid currents from waving Cilia Peristaltic contractions of the Uterine tubes |
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135. How many cells form a morula cluster?
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12-16
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136. Fluid moves out of/into to form the blastocyst
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Into
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137. The Trophoblast/inner cell mass will eventually form the placenta?
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Trophoblast
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138. The synctiotrophoblast/endometrium secretes enzymes which allow the blastocyst to implant in the uterus?
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synctiotrophoblast
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139. The amniotic cavity extends from the epiblast/hypoblast?
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Epiblast
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140. What is the function of the connecting stalk?
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It is the precursor of the umbilical cord. There are both arteries and veins in the connecting stalk, and blood cells are produced with the yolk sac and pass to the embryo
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141. The neural tube forms from the ectoderm/endoderm?
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Ectoderm
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142. What is one function of amniotic fluid?
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Shock absorption
Temperature regulation Prevents the embryo from sticking to the membranes around it |
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143. The periosteum/osteosteum contains osteoclasts?
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Periosteum
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144. What is the size of embryo at 1-8 weeks?
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1 - 0 .2mm
2 – 0.4mm 3 – 2mm 4 – 5mm 5 – 8mm 6 – 12.5mm 7 – 17mm 8 – 30mm |
